Everyone loves a surprise. Hours after announcing the existence of a new film, Michael Moore in TrumpLand, film-lovers, leftists and New Yorkers drawn to wherever the action is were lining up outside the IFC Center in Greenwich Village.

The free screening, which included a chat with the Oscar and Palme d’Or winner that lasted almost as long as the film, had a bit of a carnival atmosphere. People with megaphones, lighted signs and placards quoting Bob Avakian mixed with folks taking selfies in front of a Zoltan-esque Trump fortune-teller booth. One weary person looking for a spare ticket raised her index finger, a holdover from Grateful Dead shows, when people “need a miracle”.

The real surprise: the movie itself consisted almost exclusively of footage of one man talking.

A woman poses next to the Knockout Trump Truck outside the IFC Theater, ahead of the premiere of Michael Moore in TrumpLand. Photograph: Kena Betancur/AFP/Getty Images

Once inside, we learned what inspired the populist documentarian to shoot a new movie 11 days ago and rush it out just two weeks before the election: he is terrified.

“I was in England during Brexit week, promoting my last film. All the polls said it wouldn’t happen. They were wrong,” he said.

There’s great irony to Moore citing the Michigan primary as impetus for his new film, which is an urgent, 73-minute call to arms to get out and vote for Clinton, mixed with some jokes. Michigan is Moore’s home state and he voted for Sanders. In fact, he’s never voted for Hillary Clinton before, or any Clinton for that matter. But he felt compelled to do everything he could to support her now, in the general election.

That meant going to one of the more ardent rightwing counties in Ohio, one which he calls “the Brexit states” which also include Michigan, Wisconsin and Pennsylvania. He put on a one-man show – a mix of a TED talk with some populist Prairie Home Companion gags and prerecorded bits – and did his best to engage with undecided voters, third-party voters and, yes, even Trump voters.

Michael Moore’s surprise Trump documentary is ‘an urgent, 73 minute call to arms to get out the vote for Clinton, mixed with some jokes’. Photograph: IFC

“What this country doesn’t need is a horror movie about Donald Trump. He’s producing that himself,” Moore said. But get past the less successful gags and assertive crowd reaction shots, and Moore’s central thesis is one that has been strangely absent from the conversation: everyone should be thrilled to vote for Hillary Clinton.

What Moore does is work through his own troubled relationship with her. He hates that she voted for the Iraq war, and surely the director of Roger & Me isn’t thrilled with her ties to Wall Street. “But she’s still the same woman who gave that commencement address at Wellesley College. And we’ve got to hold her to that.”

Jokingly, he added that two years into her term, if she doesn’t make good on her promises, he will run for president himself in 2020. But first we’ve got to “stop doing end-zone dances. That’s going to get Trump elected. She is still the second most hated candidate in history, only behind Trump”.

Michael Moore In TrumpLand spends a great deal of time compassionately getting into the head of a would-be Trump voter in the “Brexit states” who deserves “the right to send a ‘fuck you’ vote”. But he urged us all to “make a party” of being able to have the first woman president and not “someone like Margaret fucking Thatcher”.

Moore’s lengthy post-screening chat was a bit of a roller coaster. For starters, he seemed exhausted, having just finished editing at 7am that day. He got emotional discussing his late mother, who chose to work at a time when wives and mothers just didn’t do that. He explained how the act of voting for Obama (and seeing his middle name Hussein on the ballot) caused him to sob, thus smudging his check mark.

He also went on a tangent about the reality television show The Bachelorette, because, at heart, Moore will always be an entertainer and a showman – the type of guy who can get Twitter trending for a full day for the release of a monologue encouraging people to vote for a candidate they may not be too enthusiastic about.

“If you leave and think, ‘Oh this was just a funny show’, I’ve failed,” he warned.